This invention relates to a connecting apparatus adapted to connect a high-speed signal line and, in particular, to a connector such as a straight-pin connector and a right-angle socket connector.
As a connector of a vertical-connection type for use in a connecting portion between a back board and a package board connected to the back board in a direction perpendicular thereto, use has heretofore been made of a right-angle socket mounted on the package board. The socket comprises a large number of contact modules and a large number of ground plates mounted to a front housing so as to be adapted to high-speed signal transmission. The contact modules and the ground plates are alternately arranged to be sandwiched by each other. Each of the ground plates is electrically connected to a circuit board by forming a ground connecting portion extracted or extended from the ground plate to be directly contacted with the circuit board or by cutting the ground plate to form a contact spring to be contacted with a contact through which electrical connection to the circuit board is achieved.
In the former technique, the ground connecting portions are located on the circuit board at positions between contact connecting portions. In case where the contact connecting portions are arranged at a high density, it is difficult to form a circuit pattern on the circuit board and to provide the ground connecting portions on the circuit board in view of space limitation. If the ground connecting portions are formed in an area except the neighborhood of the contact connecting portions, the number of the ground connecting portions is inevitably reduced and ground characteristics of the contacts is degraded. This results in deterioration in transmission characteristics.
In the latter technique, the ground plate is cut. In an area where the ground plate is cut, there arise various unfavorable phenomena, such as occurrence of crosstalk, variation in impedance characteristic, and reflections resulting therefrom. Thus, the transmission characteristics are degraded. Obviously, the degradation in transmission characteristics will be more serious with an increase in number of the contacts to be contacted with one ground plate.
Meanwhile, in differential transmission, a differential signal pair is transmitted through a pair of two contacts as one transmission line pair. Consideration will be made of the case where a pair of package boards are disposed on front and back surfaces of the back board with the back board interposed therebetween. As seen from a front side of a mounting surface of the back board, the package boards on the front and the back surfaces thereof are connected to the back board to be perpendicular to the back board and to be perpendicular to each other. The back board is provided with a straight-type pin connector including a number of pin contacts penetrating via through holes formed in the back board to protrude on the front and the back surfaces of the back board. The pin contacts are fitted into the right-angle socket attached to the package boards on the front and the back surfaces of the back board.
It is assumed that a pair of pin contacts forming a transmission line pair are aligned parallel to one package board on one of the front and the back surfaces of the back board. Then, the same pair of pin contacts are aligned perpendicular to the other package board on the other of the front and the back surfaces of the back board. In this event, in the right-angle socket connector on the one package board, transmission lines in the transmission line pair are equal in length to each other. On the other hand, in the right-angle socket connector on the other package board, the transmission lines in the transmission line pair are different in length from each other. This means that a pair of transmission lines in the transmission line pair are different in total length from each other. Therefore, a skew, i.e., a difference in propagation delay is produced in the single transmission line pair in the connector. As a result, transmission characteristics are degraded.
Furthermore, if a transmission line of a ground contact is substantially similar in section to that of a signal contact, crosstalk will easily occur between signal contacts arranged on both sides of the ground contact.
It is therefore an object of this invention to provide a connector which is reduced in space-related problems and which is improved in transmission characteristics.
It is another object of this invention to provide a connector in which crosstalk hardly occurs.
It is still another object of this invention to provide a right-angle socket connector of a vertical-connection type, which is capable of enhancing ground connection to be adapted to high-speed transmission by bringing a ground contact for high-speed transmission into contact with a ground plate to surround a signal contact.
According to an aspect of the present invention, there is provided a connector which comprises a housing, a plurality of contacts held by the housing to be arranged in a plane, a first ground plate placed between adjacent ones of the contacts, a second ground plate intersecting with the first ground plate and placed between adjacent ones of the contacts, a first contacting portion bringing at least one of the first and the second ground plates into contact with at least one of the contacts, and a second contacting portion bringing the first and the second ground plates into contact with to each other.
According to another aspect of the present invention, there is provided a connector assembly which comprises a back board having opposite surfaces and a plurality of connectors each according to the above-mentioned connector. The connectors are mounted on the opposite surfaces of the back board in positions such that the first ground plates are arranged in directions intersecting with each other.
According to still another aspect of the present invention, there is provided a connector which comprises a plurality of contacts, an insulator holding the contacts and having a window portion, and a ground plate facing the insulator. At least one of the contacts has a ground plate contacting portion connected to the ground plate. The ground plate contacting portion is connected with the ground plate through the window portion.
According to yet another aspect of the present invention, there is provided a multi-pole connector which comprises a plurality of connectors each according to the above-mentioned connector. The connectors are superposed one another in a condition where the ground plate extends between adjacent ones of the connectors. The multi-pole connector further comprises a front housing coupled to the connectors and a shield plate coupled to the front housing and holding the connectors in cooperation with the front housing to form an integral structure.